Researchers from the department of nutrition, dietetics and food at Monash University reviewed eight previous studies on the issue, and they say there is considerable evidence that gut injury and impaired function increases with exercise intensity and duration.

"The stress response of prolonged vigorous exercise shuts down gut function," said lead author Ricardo Costa.

"The redistribution of blood flow away from the gut and towards working muscles creates gut cell injury that may lead to cell death, leaky gut, and systemic immune responses due to intestinal bacteria entering general circulation.”